netdev - Re: [PATCH net-next v6 6/6] samples/bpf: add userspace example for prohibiting sockets

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Date:   Wed, 30 Nov 2016 21:59:55 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     David Ahern <dsa@...ulusnetworks.com>
Cc:     netdev@...r.kernel.org, daniel@...que.org, ast@...com,
        daniel@...earbox.net, maheshb@...gle.com, tgraf@...g.ch
Subject: Re: [PATCH net-next v6 6/6] samples/bpf: add userspace example for
 prohibiting sockets

On Wed, Nov 30, 2016 at 10:16:50AM -0800, David Ahern wrote:
> Add examples preventing a process in a cgroup from opening a socket
> based family, protocol and type.
> 
> Signed-off-by: David Ahern <dsa@...ulusnetworks.com>
...
> +++ b/samples/bpf/sock_flags_kern.c
> @@ -0,0 +1,37 @@
> +#include <uapi/linux/bpf.h>
> +#include <linux/socket.h>
> +#include "bpf_helpers.h"
> +
> +SEC("cgroup/sock1")
> +int bpf_prog1(struct bpf_sock *sk)
> +{
> +	char fmt[] = "socket: family %d type %d protocol %d\n";
> +
> +	bpf_trace_printk(fmt, sizeof(fmt), sk->family, sk->type, sk->protocol);
> +
> +	/* block PF_INET6, SOCK_RAW, IPPROTO_ICMPV6 sockets
> +	 * ie., make ping6 fail
> +	 */
> +	if (sk->family == PF_INET6 && sk->type == 3 && sk->protocol == 58)
> +		return 0;

why not to use SOCK_RAW and IPPROTO_ICMPV6 instead of constants?

Thanks for the test!